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Biomedical subjects

S D Smith

Publications and source records attributed to S D Smith.

At least 271 records · Page 15Linked to original sources
PubMed1984

Gene heterogeneity: a basis for alternative 5.8S rRNA processing.

Two bands of 5.8S rRNA were observed when the total RNA isolated from rat or mouse tissue was separated by electrophoresis on high-resolution polyacrylamide gels under denaturing conditions. The minor form, with a lower mobility, represented 15-35% of the total 5.8S rRNA, depending on the source of the tissue. Sequence analysis and the kinetics of formation showed that this minor form is elongated at the 5' end and is not a precursor. The sequence of the minor form was found to be p(C)CGAUA[CG-, five or six nucleotides longer than the major form. The minor 5.8S rRNA constituent also formed a more stable junction complex with 28S rRNA than the shorter major sequence. The rat DNA sequence that corresponds to the additional nucleotides at the 5' end of 5.8S rRNA has been reported to be -CCGTACG-[Subrahmanyam, C. S., Cassidy, B., Busch, H., & Rothblum, L. I. (1982) Nucleic Acids Res. 10, 3667-3680], a sequence which does not contain the extra adenylic acid residue at position 4 found in the minor form. This suggests that the rodent rRNA genes are heterogeneous and that the insertion of an A residue in the ribosomal precursor RNA can generate an alternate processing site.

Animals↗
PubMed1984

Utilization of a human tumor cloning system to monitor for bone marrow involvement in children with non-hodgkin's lymphoma.

The objective of this study was to evaluate the sensitivity of two methods for determining bone marrow involvement with non-Hodgkin's lymphoma. These methods were histologic review of bone marrow aspirates, and clot sections versus in vitro growth of lymphoma colonies on soft agar. Forty-two bone marrow aspirates were studied from 14 children who were without bone marrow involvement at diagnosis. There were seven bone marrow aspirates (from five patients) that had histologic evidence of metastatic lymphoma. Six of these seven specimens formed colonies in vitro. Twenty-nine of 35 histologically negative specimens showed no lymphoma colony growth. However, six histologically negative specimens (from three patients) formed lymphoma colonies. Both the Fisher's exact test and the K statistic were significant, indicating not only an association between histology and in vitro culture results, but also a close agreement. In addition, growth of lymphoma colonies in vitro was associated statistically with both a short duration of complete remission and a short duration of survival.

Adolescent↗
PubMed1984

Effects of thyroid status on clonidine-induced hypoactivity responses in the developing rat.

Clonidine-induced hypoactivity was studied in rats made neonatally hypo- and hyperthyroid (PTU or T4 administered between 1-27 days postnatally) as an indication of central presynaptic alpha 2-adrenoceptor function. Paradoxically, at 28 days postnatally both treatments caused an increase in clonidine-hypoactivity compared with untreated control animals, which was not due to sex differences amongst littermates in the various groups. It is proposed that whereas the hyperthyroid neonate data perhaps reflect an enhancement of presynaptic alpha 2 function similar to that seen in the adult rat brain, the result obtained for the hypothyroid neonates could perhaps be due to a retardation of the ontogeny of central noradrenergic neurones.

Animals↗
PubMed1984

Agrammatism in a case-inflected language: comprehension of agent-object relations.

Yugoslav agrammatic aphasics and normal control subjects were tested for comprehension of agent-object relations in a series of simple Serbo-Croatian sentences consisting of two nouns (N) and a transitive action verb (V). The availability of nominative and accusative case inflections and a semantic contrast was systematically varied across sentences. Sentences were also varied with respect to the two sequences NVN and VNN. An analysis of subjects' agent-object assignments yielded the following results: While Broca's aphasics did show some sensitivity to case inflections, their ability to process such cues was greatly impaired relative to normal subjects, for whom morphological cues were almost completely deterministic. To a lesser degree, Broca's aphasics were impaired in their ability to employ a strategy of "choose the first noun as agent" when case inflections and semantic contrasts were not available. While Broca's aphasics showed no impairment in their ability to exploit semantic contrasts for agent-object assignment, there was no absolute compensatory increase in the degree to which they relied on semantic cues. Differences in word sequence had no effect on agent--object assignment in Broca's aphasics. Finally, Broca's aphasic frequently responded unsystematically when cues to agent--object relations occurred in isolation or in competition with one another, but when there was a convergence of cues their performance approached that of normal subjects. This result was interpreted in terms of an accessing hypothesis.

Adult↗
PubMed1984

The pulmonary hemodynamic response to perioperative anesthesia in the treatment of high-risk infants with congenital diaphragmatic hernia.

The continuing high mortality in congenital diaphragmatic hernia led us to study the cardiopulmonary disturbances associated with this lesion. Since these infants infrequently have right-to-left shunting in the operating room, we adopted a treatment protocol of: continuing general anesthesia in the postoperative period using fentanyl and pancuronium; cardiac catheterization postoperatively, including placement of a pulmonary artery line and a pulmonary angiogram; rapid frequency ventilation; moderate fluid restriction; and avoidance of vasodilators until other means of management had clearly failed. Fourteen high-risk infants, presenting within 6 hours of birth, were studied and compared to 17 high-risk infants, who served as historical controls. As revealed by the physiologic data acquired in the catheterization laboratory, high-risk infants divided into "Responder" and "Nonresponder" groups. Seven of 10 "Responders" actually shunted left to right during the catheterization, demonstrating a low pulmonary vascular resistance. Seven of 10 subsequently demonstrated significant right-to-left shunting at the level of the ductus and the foramen ovale, indicating the hyperreactivity of the pulmonary vascular bed. All but one was managed successfully by ventilatory adjustments and deepening of the level of anesthesia. "Nonresponders" had a fixed right-to-left shunt unresponsive to any medical or ventilatory manipulation. All "Nonresponders" died. Pulmonary angiography suggested a smaller diameter of the affected pulmonary artery compared to the main pulmonary artery in the "Nonresponders." This implies true hypoplasia resulting in a vasculature too small to accept a full cardiac output. Survival in the treatment group "Responders" was eight of 10 (80%) v seven of 14 (50%) in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1984

Monoclonal antibody and enzymatic profiles of human malignant T-lymphoid cells and derived cell lines.

Recently, four distinct cell lines were established from patients whose malignancies had been defined by immunological and biochemical markers. Each patient had a distinct subtype of a T-cell cancer, and each possessed elevated adenosine deaminase and reduced nucleoside phosphorylase activity. Cell lines cultured in vitro possessed the same basic immunophenotype and biochemical enzyme activity as the patients' original malignant cells. In a direct comparison of the immunophenotype of the cell lines and the patients' malignant cells, full concordance existed for 48 of 52 paired antibody tests performed. However, when compared to the corresponding patient's sample, each cell line showed some minor changes in antigen expression or enzyme level. Antigen loss, de novo antigen expression, or elevated adenosine deaminase levels occurred in the cell lines, and these changes were stable on repeated analysis. While there was good general concordance between the patient's cancer and the established cell line, minor biological differences in the cell lines may reflect cellular maturation or subpopulation selection in vitro.

Adenosine Deaminase↗
PubMed1984

The STA operation for the pronated foot in childhood.

The STA operation is a modified subtalar arthroereisis that uses an endoprosthesis manufactured from ultrahigh-molecular-weight polyethylene. It is fashioned into the shape of a small peg and implanted into the dorsal surface of the calcaneus. Its purpose is to eliminate abnormal pronation, correct heel valgus, and produce an increase of the medial longitudinal arch.

Adolescent↗
PubMed1983

In vitro sensitivity of normal granulocytic and lymphoma colonies to vinca alkaloids.

Recently, a colony-forming assay was developed in our laboratory for pediatric malignant lymphoid diseases. This assay supports the growth of lymphoma colonies (ML-CFC) as well as normal granulocytic colonies (CFU-C) and thus a direct comparison between the antineoplastic and myelosuppressive effects of a drug can be determined. To test specificity of this in vitro assay to structurally similar drugs, the inhibitory effects of three vinca alkaloids (vincristine, vindesine, vinblastine) on ML-CFC (B-, T-, pre-T-cell types) and CFU-C was determined. Our results demonstrate that all three vinca alkaloids were active agents in vitro and that a direct dose response effect occurred once a threshold dose was reached. Each vinca alkaloid had a different pattern of inhibitory effect on ML-CFC and CFU-C suggesting an inherent difference in drug metabolism by these cells. Also, based on the dose inhibiting 50% of colony formation, vinblastine was 94 times more inhibitory against malignant B-cell ML-CFCs than against granulocytic CFU-C.

B-Lymphocytes↗
PubMed1983

Cytogenetic studies of a patient with mosaicism of isochromosome 13q and a dicentric (Y;13) translocation showing differential centromeric activity.

A case is presented in which both an isochromosome and a dicentric translocation with differential centromere activity are found in one individual. Three karyotypes are present: 46,XY, -13, + i(13q)/45,X, -13, + psu dic(13)t(13;Y)/45,X, -13, + psu dic(Y)t(Y;13). The isochromosome 13q is found in 23% of cells in blood and 5% in skin. The dicentric (Y;13) chromosome in all of the remaining cells displays differential centromeric activity; the ratio of cells with the active 13 centromere to the active Y centromere is about 3.5:1. The formation of the isochromosome 13q was a de novo gametic event. The translocation producing the dicentric occurred after fertilization with the breakpoints at band Yq12 and the juxta-centromeric region of the isochromosome 13. The finding of differential centromeric activity in this chromosome indicates that centromere inactivation is not always permanent in a dicentric translocation.

Centromere↗
PubMed1983

Effects of (E)-5-(2-bromovinyl)-2'-deoxyuridine on proliferation of human fibroblasts, peripheral blood mononuclear cells, and granulocyte-monocyte progenitor cells in vitro.

Inhibition of human fibroblasts, granulocyte-monocyte progenitor cells, and lymphocytes was observed at (E)-5-(2-bromovinyl)-2'-deoxyuridine concentrations ranging from 21 to 197 micrograms/ml. These concentrations were 10- to 100-fold above usual serum concentrations after oral administration. (E)-5-(2-Bromovinyl)-2'-deoxyuridine compares favorably with currently used antivirals in terms of in vitro myelotoxicity and immunotoxicity.

Antiviral Agents↗
PubMed1983

Genetic influences on learning disabilities and speech and language disorders.

This paper is a comprehensive review of known examples of genetically influenced learning disabilities (LDs) and speech and language disorders (SLDs). The review is divided between 2 broad classes of studies: (a) those which begin with an LD or SLD phenotype that appears to be familial and attempt to learn more about the specifics of genetic transmission, if any; and (b) those which begin with a group of individuals, all of whom share a given documented genetic risk factor, to see if it leads to a specific LD or SLD. Included in the first category are familial dyslexia, stuttering, and other speech and language disorders. In the second category are included sex chromosome anomalies, treated PKU, and minor autosomal anomalies. Issues of definition, variability, and developmental changes in the cognitive phenotype are discussed throughout. The implications of this work for our understanding of cognitive development and its bases in brain development and genetics are also discussed.

Adolescent↗
PubMed1983

Psychological correlates of compliance.

A urinary assay (17 kgs/creatinine) was used to measure compliance in 31 acute lymphocytic leukemia patients under 15 years of age receiving oral prednisone. Demographic data and psychological test responses of patients and their parents were correlated with the urinary assays. Results indicated that while the rate of compliance was the same for boys and girls, the psychological correlates were very different. Parental personality traits and attitudes were more involved with boy's compliance than with girl's. Some of the parent variables associated with compliance in boys were hostility, anxiety, and obsessive-compulsive behavior. Parents described compliant boys as vulnerable. These traits usually are considered maladaptive but in this case appear to facilitate boy's compliance. For girls, far fewer parent variables were associated with compliance. Parents seemed to have less worry and concern about their daughters and presumably give them the responsibility for their own medication. It was the girl's own anxiety which predicted compliance.

Adolescent↗
PubMed1983

Bioelectric repair of metatarsal nonunions.

An exciting new development in the field of bone physiology has been the discovery of electrical potentials in stressed bone and the relation of this knowledge to Wolff's law. The application of these discoveries for the treatment of nonunions by exogenous bioelectric potentials via direct current and pulsed electromagnetic fields has been a major development in orthopedic surgery. To date, the literature reports the use of this new treatment modality in the large long bones of the extremities. The authors have utilized these techniques to repair nonunions of the metatarsals and, in the process, have adapted some of the principles for the small bones of the foot.

Adult↗
PubMed1983

The relationships of age, sex, ethnicity, and weight to stereotypes of obesity and self perception.

In order to assess the relationships of stereotypes of obesity and of self perceptions to age, sex, ethnicity and weight, 447 adults and children varying in sex, ethnic background and weight rated 12 line drawings of people who varied in age, sex and weight, as well as giving self ratings on similar scales. The normal weight stimuli, compared with the fat oe thin ones, were more wanted as friends and were seen as happier, having more friends, being smarter, and better looking but less lonely and mean. The thin stimulus figures were seen as having more friends, being better looking, smarter and meaner than the fat ones. These trends held for both the sexes, all ages, all ethnic groups, and children of all weights. Names or nicknames assigned to the stimuli also reflected stereotypes: Fat nicknames were given primarily to the fat stimuli; Thin and Height-related ones were given to the thin stimuli; and the average stimuli received more Neutral/Normal and Clearly Positive and fewer Other/Ambiguous and Clearly Negative names. Self evaluations suggested that fifth graders and American Indians were lowest in self concept on some scales, consistent with other research. Overweight subjects were generally similar to average and underweight ones in self ratings, contrary to expectation. Apparently these subjects did not perceive themselves as negatively as previous research and their ratings of the obese stimuli might have caused us to expect.

Adult↗
PubMed1983

Arthrorisis by means of a subtalar polyethylene peg implant for correction of hindfoot pronation in children.

A modified subtalar arthrorisis is obtained by implantation of an endoprosthesis manufactured from ultrahigh molecular weight polyethylene. It is fashioned into the shape of a peg and implanted into the dorsal surface of the calcaneus just anterior to the posterior facet of the subtalar joint and fixed with polymethylmethacrylate. The purpose of the implant is to eliminate abnormal pronation, correct heel valgus, and produce an increase of the medial longitudinal arch in the growing child.

Calcaneus↗